Don’t the snow and ice at the Earth’s poles also help cool the Earth by reflecting the sun’s rays?
Yes. Snow and ice, being white, have a high “albedo,” or degree of reflectivity. They reflect up to 90 percent of the sunlight they receive. Regions covered by snow and ice and having sub-zero temperatures year-round, including Antarctica, the Arctic Ocean, Greenland, northern Canada, northern Siberia, and most of the high mountain ranges in the world, make up what’s called the “cryosphere.” Without the cryosphere reflecting sunlight away from the Earth, the Earth’s atmosphere would be warmer. However, once global warming has begun and reflective snow cover begins to vanish, more sunlight will be absorbed, the atmosphere will become even warmer, more snow and ice will vanish, and so on in a self-perpetuating cycle.
